Microstructural features influencing the mechanical performance of the Brazil nut (Bertholletia excelsa) mesocarp

Autor(es)

Sonego, Marilia ^[1] ; Madia, Mauro ^[2] ; Eder, Michaela ^[3] ; Fleck, Claudia ^[4] ; Pessan, Luiz A. ^{[5, 1]}

Afiliação do(s) autor(es)

^[1] Fed Univ Sao Carlos UFSCar, Grad Program Mat Sci & Engn PPGCEM, BR-13565905 Sao Carlos, SP - Brazil

^[2] Bundesanstalt Mat Forsch & Prufung BAM, D-12205 Berlin - Germany

^[3] Max Planck Inst Colloids & Interfaces, Dept Biomat, Muhlenberg 1, D-14476 Potsdam - Germany

^[4] Tech Univ Berlin, Mat Sci & Engn, D-10623 Berlin - Germany

^[5] Univ Fed Sao Carlos, Dept Mat Engn, Via Washington Luiz, Km 235, BR-13565905 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS; v. 116, APR 2021.
• Citações Web of Science: 2

Resumo

Brazil nut (Bertholletia excelsa) fruits are capable of resisting high mechanical forces when released from trees as tall as 50 m, as well as during animal dispersal by sharp-teethed rodents. Thick mesocarp plays a crucial part in seed protection. We investigated the role of microstructure and how sclereids, fibers, and voids affect nutshell performance using compression, tensile and fracture toughness tests. Fractured specimens were analyzed through scanning electron microscopy (SEM) and microtomography (microCT). Mesocarp showed high deformability (strain at max. stress of similar to 30%) under compression loading, a critical tensile strength of similar to 24.9 MPa, a Weibull modulus of similar to 3, and an elastic modulus of similar to 2 GPa in the tensile test. The fracture toughness, estimated through the work of fracture of SENB tests, reached similar to 2 kJ/m(2). The thick and strong walls of mesocarp cells, with a weaker boundary between them (compound middle lamella), promote a tortuous intercellular crack path. Several toughening mechanisms, such as crack deflection, breaking of fiber bundles, fiber pullout and bridging as well as crack branching, occur depending on how fiber bundles and voids are oriented. (AU)

• Processo FAPESP: 15/25523-1 - Biomimetismo do ouriço da castanha-do-pará: estrutura e análise de falhas
• Beneficiário: Marilia Sonego
• Modalidade de apoio: Bolsas no Brasil - Doutorado